1. Field
The present disclosure relates to a method of correcting a signal of an absolute encoder and a method of calculating an angle using the corrected signal.
2. Description of Related Art
An encoder is a device that detects the rotating angular speed and location of a rotating object. The encoders can be divided into an optical encoder and a magnetic encoder in accordance with units that detect rotation. Also, the encoders can be divided into an incremental encoder that measures a relative location with respect to a certain reference, and an absolute encoder that measures an absolute location regardless of power supply.
The magnetic encoder generates an output signal that can detect the rotating angular speed and the rotation location using a magnetic substance rotating together with a rotating object. The output signal of the magnetic encoder includes a pair of a sine wave and a cosine wave, based on an induced voltage of a rotating magnetic field, and can detect the rotation location and rotation speed from phases of the two waveforms. However, magnetic encoders are vulnerable to noise, phase fluctuations, DC offsets, amplitude fluctuations, and waveform distortions in the output signal. Accordingly, there have been many studies on a technique for removing a phase difference from an output signal of the magnetic encoder.